Such apparatuses comprise a vat or receptacle which is generally substantially cylindrical or substantially spherical in shape and which contains an agitating moving member fitted to the outlet shaft of a motor and stepdown gear unit providing rotary drive. The agitating moving member is constituted by a hub from which there project a plurality of blades or vanes of a shape which is selected as a function of the nature of the products and of the work or treatment to be performed, so that uniform mixing can be effectively sustained throughout the bulk of the products contained in the receptacle.
In order to illustrate the prior art on this topic, reference may be made to the teaching of French patents numbered 2 052 018 (69/22 862) and 2 273 582 (74/19 418).
Although the agitating moving members known at present generally give satisfaction with respect to uniformity and thorough mixing of the products contained in the receptacle, it turns out that such apparatuses, taken as a whole, are not suitable in all cases for properly performing the operations of mixing, homogenizing, stirring, or treatment.
Depending on the processes that are to be performed, it often happens that proper operation requires heat to be added to or taken from the mixture in order to maintain a core temperature which is compatible with the mixing, homogenizing, or processing to be performed. It also often happens that a need arises to act on thermal parameters in temporary manner, for example during a reaction stage, with the agitating moving member being required at other times merely to maintain stirring.
In the past, such a thermal parameter has been adequately controlled by means of heat-conveying fluids flowing inside a double-walled vessel. Heat exchange takes place by conduction through the wall of the vessel which constitutes a barrier impeding heat exchange. Under such conditions it becomes difficult to inject or remove heat to or from the core of the moving mass inside the vat or the receptacle, or else to or from the vicinity of the agitating moving member.
In order to remedy this drawback, proposals have been made, e.g. in French patent number 1 460 908, to provide blades or vanes of an agitating module which are hollow, so as to delimit an internal go-and-return circuit for a heat-conveying fluid.
Using such technical means, it is possible to add or subtract heat to or from the moving mass and be certain that heat transmission actually takes place, given that the various blades of the agitating module are permanently in contact with the core of the mass to be stirred or mixed.
Although such a proposition solves the problem posed, it suffers from posing a secondary problem, namely the problem of providing a suitable hub capable of being fitted to the drive shaft and of withstanding a high level of mechanical loading due to its transmission of the drive torque provided by the driving system used.
Such a hub must also be suitable for providing the go-and-return flow of the heat-conveying fluid between the blades or vanes and a go-and-return circuit connected to the drive shaft of such an agitating module. Such fluid transmission must naturally be provided in fluid-tight manner.
Another requirement of such a hub lies in the need for it to provide easy and quick access to its various component parts when a leak needs to be repaired or when a blade needs to be replaced, e.g. because it has been damaged, at least in part.
These requirements are not solved by above-mentioned French patent number 1 460 908, nor by the teaching of the following patent publications No.: DE 19 26 704, U.S. Pat. No. 3 241 606, and CH 643 153, none of which pays particular attention to the specific problem of how the blade hub should be constituted.
An object of the invention is to satisfy these difficulties taken as a whole.